Do plants have their own form of conciousness?

'Most people consider plants to be bordering on machines, wholly determined by external factors' [Reuters]

Vitoria-Gasteiz, Spain - When, almost two months ago, I penned an op-ed titled If Peas Can Talk, Should We Eat Them? for "The Stone" philosophy section of the New York Times, I did not expect that it would stir as much controversy as it did in the following weeks.

My argument was attacked by everyone from Christian fundamentalists to vegans and from neuroscientists to humanist rationalists. Since then I have responded to some of the criticisms in another Times piece, Is Plant Liberation on the Menu? and participated in a debate on plant ethics with the animal rights advocate, Professor Gary Francione. Despite the occasionally heated polemics, I take the interest in this topic to be an encouraging sign that the current attitudes toward plants may be starting to shift. The sheer fact that they can become the subjects of intense discussion and debate implies that plants do not have to be forever confined to the inconspicuous background of our everyday lives.

"Some plants can defend themselves by releasing volatile chemicals that attract the predators of the very herbivores who feed on them."

It seems, however, that all this is but the tip of an iceberg now emerging from the stagnant waters of humanist ethics. Even a cursory consultation with the findings of contemporary botany is enough to gauge how research is rapidly dismantling what we thought we knew about plants. Not only can some plants defend themselves by releasing volatile chemicals that attract the predators of the very herbivores who feed on them but they can also differentiate between members of the same species and "strangers", altering their root growth in response to the identity of the neighbouring plant.

At the moment, our political and ethical thinking about vegetation is lagging behind these discoveries. Most people consider plants to be bordering on machines, wholly determined by external factors. And nothing is more conducive to the deepening global environmental crisis than the complacent and un-problematised equation of trees with raw materials - available for unlimited human consumption.

Without prejudice

In the recent debate, for example, Prof Francione compared a plant to an inanimate object, a bell triggered from the outside. Clearly, if one adheres to an ethical program inspired by 19th century utilitarianism, one would want to convey a 19th century idea of what is a plant, as opposed to an animal. The desire of vegans to enforce the conceptual dividing lines between sentience and non-sentience prompts them to blur the obvious distinctions between living plants and inanimate things.

Although they can be chemically manipulated into blossoming or delayed in the process of ripening, plants and their parts - flowers, fruit etc - are growing beings, whose hormonal, biochemical and cellular processes remain, to this day, largely unknown to us. Overlooking this complexity results in a thinking that is simplistic. Worse still, it gives carte blanche to the forces of agro-capitalism bent on commodifying every aspect of human and nonhuman lives.

"Although plants might not have the capacity to experience pain, they relate to the world in ways often drastically divergent from those employed by humans or animals."

The challenge is to initiate a dialogue between the scientific and the philosophical issues related to plant life, without allowing prejudice to creep into either. In this respect, the fundamental philosophical questions here are: How are we to think through the foundations for ethical thought and action? And is this foundationalist approach still justifiable, relevant or useful? Are we to treat ethically only those living beings that most resemble us, ie: sentient animals? Is empathy the ultimate basis for determining how to treat someone or something? Or, is an ethics of difference (or otherness) needed so as to account for our conduct toward life forms that do not facilitate our sympathetic self-recognition?

I believe that this last point is especially relevant to the ethics of plant life. Although plants might not have the capacity to experience pain, they relate to the world in ways often drastically divergent from those employed by humans or animals. Let us take the example of language. It would have been fair to say that, in talking about "plant communication", we merely project our own realities onto plants, if (and only if) communication were a uniquely anthropomorphic phenomenon.

Conversely, if human language is just one example of what language "as such" - as Walter Benjamin, Hans-Georg Gadamer and Jacques Derrida have acknowledged in the course of the 20th century - then this manner of speaking is not our careless projection of our artifacts onto the nonhuman world, but a definitive departure from a narrowly anthropocentric paradigm.

Why should we care?

Without a doubt, the questioning of what plants are and how we should treat them is perceived as threatening by members of various interest groups. I have already touched upon the negative vegan reaction, which is nevertheless inexplicable, given that they had to deal with analogous criticisms occasioned by their attempts at the extension of legal and other rights to animals. Here is a comparison of the most common attacks on proponents of animal ethics and plant ethics, respectively:

Why should we care about animals, when humans are dying of hunger and genocide?

Why should we care about plants, when animals are suffering and are killed for food?

Because animals are not rational beings, their lives are impoverished and less valuable, compared with those of humans.

Because plants are not sentient beings, their lives are impoverished and less valuable, compared with those of animals.

Where do we draw the line if we admit animals into our moral considerations? Will plants be next?

Where do we draw the line if we admit plants into our moral considerations? Will bacteria be next?

If, in each of these cases, the critic fails to give either animals or plants their due, it is because these and all other beings are slotted into an objectively fixed hierarchy with humanity at its apex. (For some, the Supreme Being remains God who presides over the rest of this ladder of beings. Christian fundamentalists who pour their scorn on plant ethics do so because it puts into question the rigid theological order wherein plants are inferior, and, hence, contradicts the word of God.) It does not occur to those who adhere to hierarchies of being and value that the categories comprising them are not discrete and that, for instance, something of animal and plant natures survives in humans.

"Those who think that drawing attention to the unlimited violence perpetrated against plants is a distraction from their concern for animals are the unfortunate victims of erroneous thinking."

Compared with the horrific abuse of animals, which undoubtedly intensified with the industrialisation of agriculture, our comportment toward plants is less disturbing because, after all, a felled tree does not scream in pain as a slaughtered pig does. But this does not mean that the ongoing exploitation of plant life ought to be condoned.

To call attention to the need for justifying our otherwise unbridled instrumentalisation of vegetation is not to argue that animals should continue to suffer in industrial farm settings and slaughterhouses as well. This is a non sequitur - a conclusion that does not follow from the preceding premise and an appalling piece of fallacious thinking. Those who think that drawing attention to the unlimited violence perpetrated against plants is a distraction from their concern for animals are the unfortunate victims of this crude fallacy.

Plant conciousness?

Plant ethics does not compete for a "pet cause" with animal ethics; rather, the general idea behind it is that choices we did not deem either moral or immoral in the past are laden with serious consequences to everything (and everyone) affected. Granted: the dismantling of the hierarchies of being and value wreaks havoc in a dogmatically ordered ontological and moral universe of philosophy still insufficiently suffused with the spirit of criticism. Such deconstruction does not, however, culminate in the erasure of differences between and within all beings - but in the exact opposite: a flourishing of difference outside the confines of its hierarchical arrangement.

The other source of anxiety lies hidden in the responses of neuroscientists, who have long reduced human consciousness to a series of cellular and molecular interactions. Plants, of course, do not have a central nervous system but this does not prevent them from sending complex bio-chemical messages, for instance, through their roots and altering their growth patterns as a result.

"We should interpret the results of current plant intelligence studies in botany as a wake-up call to philosophers."

Evidence for the non-metaphorical memory of light residing in plant leaves adds insult to the injury suffered by the argument of those who still insist on the exceptionalism of the central nervous system. In other words, when consciousness is wholly embedded in its biochemical substratum, it becomes increasingly indistinguishable from the cellular and molecular processes of other, presumably nonconscious organisms, such as plants. The freedom (or plasticity) of plants is the obverse of the deterministic stricture, into which neuroscience has forced the grounds for human conduct.

The dialogue between the defenders and detractors of plant life is nothing new. In Ancient Greece, a tremendous conceptual-methodological gap was evident between the thought of Aristotle and that of his best-known student, Theophrastus. Among other writings, Aristotle bequeathed to us detailed studies of animals and their "parts", while Theophrastus left behind voluminous works, including Enquiry into Plants and De Causis Plantarum.

The lineage Western philosophy followed was undoubtedly Aristotelian, in that it privileged the animal understanding of humans, variously defined as "political animals" or "animals endowed with logos" (reason, speech etc). But what if subsequent philosophers were to pursue a Theophrastean line of thinking, focusing on the vegetal heritage in us? What if they were to pay just a fraction of the attention Theophrastus devoted to plant species and life processes?

Perhaps, in that case, the idea of plant ethics would not have sounded so outlandish to professional academics and members of the general public alike, steeped, whether consciously or not, in the Aristotelian tradition that has become a part of our common sense.

We should interpret the results of current plant intelligence studies in botany as a wakeup call to philosophers, who must begin to imagine the contours of this other mode of thinking - a discipline that has much to learn about and from plants.

Michael Marder is Ikerbasque Research Professor of Philosophy at the University of the Basque Country, Vitoria-Gasteiz. His most recent book, Plant-Thinking: A Philosophy of Vegetal Life is forthcoming from Columbia University Press later this year. His website is www.michaelmarder.org.